Crystallization Mechanism in Spark Plasma Sintered Bulk Metallic Glass Analyzed using Small Angle Neutron Scattering

Understanding the thermal stability of metallic glasses is critical to determining their safe temperatures of service. In this paper, the crystallization mechanism in spark plasma sintered Fe 48 Cr 15 Mo 14 Y 2 C 15 B 6 metallic glass is established by analyzing the crystal size distribution using x...

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Bibliographic Details
Published in:Scientific reports 2020-02, Vol.10 (1), p.2033-2033, Article 2033
Main Authors: Paul, Tanaji, Singh, Ashish, Littrell, Kenneth C., Ilavsky, Jan, Harimkar, Sandip P.
Format: Article
Language:English
Subjects:
639/166/988
639/301/1023/1026
639/301/1023/218
639/301/930/12
Annealing
Chromium
Crystallization
Crystals
ENGINEERING
Entropy
Humanities and Social Sciences
Maximum entropy
Micrography
multidisciplinary
Neutron scattering
Neutrons
Science
Science (multidisciplinary)
Size distribution
Thermal stability
Transmission electron microscopy
X-ray diffraction
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Summary:Understanding the thermal stability of metallic glasses is critical to determining their safe temperatures of service. In this paper, the crystallization mechanism in spark plasma sintered Fe 48 Cr 15 Mo 14 Y 2 C 15 B 6 metallic glass is established by analyzing the crystal size distribution using x-ray diffraction, transmission electron microscopy and in-situ small angle neutron scattering. Isothermal annealing at 700 °C and 725 °C for 100 min resulted in the formation of (Fe,Cr) 23 C 6 crystals, measured from transmission electron micrographs, to be from 10 to 30 nm. The small angle neutron scattering intensity measured in-situ , over a Q-range of 0.02 to 0.3 Å −1 , during isothermal annealing of the sintered samples, confirmed the presence of (Fe,Cr) 23 C 6 crystals. The measured scattering intensity, fitted by the maximum entropy model, over the Q-range of 0.02 to 0.06 Å −1 , revealed that the crystals had radii ranging from 3 to 18 nm. The total volume fraction of crystals were estimated to be 0.13 and 0.22 upon isothermal annealing at 700 °C and 725 °C for 100 min respectively. The mechanism of crystallization in this spark plasma sintered iron based metallic glass was established to be from pre-existing nuclei as confirmed by Avrami exponents of 0.25 ± 0.01 and 0.39 ± 0.01 at the aforesaid temperatures.
ISSN:2045-2322
2045-2322
DOI:10.1038/s41598-020-58748-3